Appendix b calibrating gas mixtures, B.1 acquisition, preparation, and handling, B.1.1 how to establish the desired concentrations – INFICON HAPSITE ER Chemical Identification System User Manual
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HAPSITE ER Operating Manual
Appendix B
Calibrating Gas Mixtures
B.1 Acquisition, Preparation, and Handling
CAUTION
Failure to calibrate the instrument may give you
inaccurate identifications when sampling.
WARNING
When using chemicals, wear the appropriate PPE
according to the MSDS.
The HAPSITE (or any GC/MS instrument) must be calibrated at one or more
concentration levels of the organic compound(s) of interest for quantitative analysis
of these Target Compounds. In the case of the HAPSITE, the Target Compounds
must be supplied to the instrument as a gaseous mixture of known volume/volume
composition (mole/mole % or ppmv levels in air or Nitrogen) and at atmospheric
pressure.
There are a number of important factors to consider in acquiring, preparing, and
handling gaseous standard calibration mixtures. These can be organized in three
groups:
1
How to establish the desired concentrations of the required compounds. See
2
Correct delivery of the mix to the inlet of the HAPSITE. See
.
3
Gas cylinder safety, contamination checks and corrective
steps in the equipment. See
.
B.1.1 How to Establish the Desired Concentrations
There are two basic ways to obtain several concentrations of a given mix of
compounds. The most obvious is to buy the compounds, premixed to specification,
in cylinders containing the several concentrations desired. The second is to buy a
master cylinder of the compounds at the highest concentration needed, and dilute
to the lower required concentrations. Each of these options is discussed below.